1993 Fiscal Year Final Research Report Summary
Basic Study of Laser Beam Applications to Space
| Project/Area Number |
04452188
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| Research Category |
Grant-in-Aid for General Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Research Field |
情報工学
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| Research Institution | THE INSTITUTE OF SPACE AND ASTRONAUTICAL SCIENCE |
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Principal Investigator |
TAKANO Tadashi The institute of Space and Astronautical Science Radio Tracking Professor, 電波追跡工学, 教授 (80179465)
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| Co-Investigator(Kenkyū-buntansha) |
YAMADA Takahiro The Institute of Space and Astronautical Science Radio Tracking Associate Profes, 符号、信号理論, 助教授 (50167714)
FUJII Youichi The Institute of Industrial Science, University of Tokyo Electronics Engineering, 生産技術研究所・光電子工学, 教授 (00013110)
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| Project Period (FY) |
1992 – 1993
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| Keywords | Optical antenna / Antenna gain / Mirror shaping / Manufacturing error / Electrooptical constant measurement / photo refractive sentitivity / Machzehnder interferometer / Adaptive coding |
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| Research Abstract |
As for optical antennas, a computer program has been made to shape reflectors. It is shown that the antenna gain can be improved by 1.5dB and the weight can be reduced by 40 percent in comparison with Gaussian optics. Next, the characteristics degradation due to support structures and manufacturing errors is analyzed for the case of dual reflector antennas. It is clarified that, If the manufacturing error amounts to be 5mmu in thickness, the aperture distribution should be tapered from a rectangular pattern at the shoulders, and the F/D value should be larger than 0.5. The reflector curves are typically aspheherical ones.
An optical antennas has been manufactured by an NC machine, and measured using the near-field method. The amplitude distribution is close to the desired one. Phase distribution in the near field and the far field patterns should be measured later.
In order to measure electrooptical contants which play an important role in the interference phenomena, a simplified and highly accurate measurement facility is realized with amplitude modulation scheme. The electrooptical constant of a proton-exchanged LiNb03 waveguide has been successfully obtained. And the photo refractive sensitivity has been measured quantitatively for the first time.
The coding scheme to adapt the coding ratio according to the ratio of optical signal power and the noise power is proposed.
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